Short answer: $ ssh-keygen -p This will then prompt you to enter the keyfile location, the old passphrase, and the new passphrase (which can be left blank to have no passphrase). If you would like to do it all on one line without prompts do: $ ssh-keygen -p [-P old_passphrase] [-N new_passphrase] [-f keyfile] Important: … Read more
I’d use tr: tr < file-with-nulls -d ‘\000’ > file-without-nulls If you are wondering if input redirection in the middle of the command arguments works, it does. Most shells will recognize and deal with I/O redirection (<, >, …) anywhere in the command line, actually.
Early versions of unix measured system time in 1/60 s intervals. This meant that a 32-bit unsigned integer could only represent a span of time less than 829 days. For this reason, the time represented by the number 0 (called the epoch) had to be set in the very recent past. As this was in … Read more
Unix uses 0xA for a newline character. Windows uses a combination of two characters: 0xD 0xA. 0xD is the carriage return character. ^M happens to be the way vim displays 0xD (0x0D = 13, M is the 13th letter in the English alphabet). You can remove all the ^M characters by running the following: :%s/^M//g … Read more
The problem is that your input file uses DOS line endings of CRLF instead of UNIX line endings of just LF and you are running a UNIX tool on it so the CR remains part of the data being operated on by the UNIX tool. CR is commonly denoted by \r and can be seen … Read more
A write that’s under the size of ‘PIPE_BUF’ is supposed to be atomic. That should be at least 512 bytes, though it could easily be larger (linux seems to have it set to 4096). This assume that you’re talking all fully POSIX-compliant components. For instance, this isn’t true on NFS. But assuming you write to … Read more
you can try stdbuf $ stdbuf –output=L ./a | tee output.txt (big) part of the man page: -i, –input=MODE adjust standard input stream buffering -o, –output=MODE adjust standard output stream buffering -e, –error=MODE adjust standard error stream buffering If MODE is ‘L’ the corresponding stream will be line buffered. This option is invalid with standard … Read more
In simple words, when you open a file, the operating system creates an entry to represent that file and store the information about that opened file. So if there are 100 files opened in your OS then there will be 100 entries in OS (somewhere in kernel). These entries are represented by integers like (…100, … Read more
awk ‘!seen[$0]++’ file.txt seen is an associative array that AWK will pass every line of the file to. If a line isn’t in the array then seen[$0] will evaluate to false. The ! is the logical NOT operator and will invert the false to true. AWK will print the lines where the expression evaluates to … Read more
Say: sed “s|\$ROOT|${HOME}|” abc.sh Note: Use double quotes so that the shell would expand variables. Use a separator different than / since the replacement contains / Escape the $ in the pattern since you don’t want to expand it. EDIT: In order to replace all occurrences of $ROOT, say sed “s|\$ROOT|${HOME}|g” abc.sh